Operating mechanism for high tension electric switch gear

ABSTRACT

Operating mechanism for high tension electric switch gear comprising hydraulic cylinder means for reciprocating a rack, a pinion engaged with the rack for rotation thereby, and a three bar toggle linkage connected between said pinion and the rotary stack of the switch for operating the switch; said mechanism being characterized by its economy, compactness, foolproof operation, safety features and power.

United States Patent Weston et a1.

1 Dec. 25, 1973 OPERATING MECHANISM FOR HIGH TENSION ELECTRIC SWITCHGEAR Inventors: Donald E. Weston, East Sebago,

Maine; Julius W. Timmerman, Brookfield, Wis.

11. K. Porter Company, Inc., Chicago, 111.

Filed: Mar. 1, 1971 Appl; No.: 119,549

Assignee:

1.1.5. Cl 91/418, 74/89.l7, 92/136, 200/48 Int. Cl. Fl5b 11/08 Field ofSearch 74/89.l7, 520, 422, 74/29; 60/52 R; 200/48; 91/418; 92/136References Cited UNITED STATES PATENTS 8/1937 Milliken 200/48 3,165,2911/1965 Osen 74/520 3,338,140 8/1967 Sheesley 74/89.l7 1,616,841 2/1927Beebe 60/52 R 3,172,182 3/1965 Assmann 74/520 3,459,056 8/1969 Lea 74/29Primary Examiner-Charles J. Myhre Assistant Examiner-Wesley S. Ratliff,Jr. Att0rneyGary, Juettner, Pigott & Cullinan [5 7] ABSTRACT Operatingmechanism for high tension electric switch gear comprising hydrauliccylinder means for reciprocating a rack, a pinion engaged with the rackfor rotation thereby, and a three bar togglelinkage connected betweensaid pinion and the rotary stack of the switch for operating the switch;said mechanism being characterized by its economy, compactness,foolproof operation, safety features and power.

5 Claims, 3 Drawing Figures PAIENIEBHEBM 3,780,625

SHEET 2 [1F 2 OPERATING MECHANISM FOR HIGH TENSION ELECTRIC SWITCH GEARBACKGROUND OF THE INVENTION High tension electric switch gear,especially outdoor disconnect switches, become quite mammoth and aresubject to severe weather conditions, such for example as heavy icing.Consequently, they require extremely powerful operating mechanisms.Usually, the switch is operated upon rotation of a shaft or an insulatorstack which aids in supporting the switch in insulated position aboveground and from grounded supporting structures; the shaft or stack beingrotated by means of a crank arm connected thereto and a reciprocablelink pivotally connected to the crank arm for oscillating the samethrough a predetermined arc. Heretofore, such mechanisms have beenexpensive, frequently of questionable reliability and serviceability,and often underpowered.

SUMMARY OF THE INVENTION The present invention provides a highlyimproved switch operating mechanism characterized by the combination ofa hydraulic cylinder power input, a rack and pinion drive, and a threebar toggle linkage interconnecting said drive and the aforesaid rotaryshaft or stack; the mechanism providing significant advantages in termsof each of economy, reliability, serviceability, power output andsafety.

Other objects and advantages of the invention will become apparent fromthe following detailed description, as taken in conjunction with theaccompanying drawings:

THE DRAWINGS FIG. 1 is a front view of an electrical switch embodyingthe operating mechanism of the invention;

FIG. 2 is an enlarged top plan view of the switch showing the relativepositions of the switch blade and the three bar toggle linkage in theopened and closed positions of the switch; and

FIG. 3 is a further enlarged elevational view of the remainder of theoperating mechanism.

DETAILED DESCRIPTION In order to acquaint those skilled in the art withthe manner of making and using my improved switch operating mechanism, Ihave shown and will now describe what I presently regard to be the bestmode of carrying out the invention.

For purposes of illustration, the operating mechanism of this inventionhas been shown in FIGS. 1 and 2 as associated with a relatively simpleside break disconnect switch adapted for outdoor service. The switchcomprises a base 10, a stationary insulator stack 12 extending upwardlyfrom adjacent one end of the base and carrying a stationary contact 14at its upper end (which contact is preferably of the type shown anddescribed in the co-pending application of Donald E. Weston, Ser. No.47,429, filed June 18, 1970), a rotatable insulator stack 16 journaledon the base adjacent the opposite end thereof and extending upwardlytherefrom, and a movable switch blade 18 carried on the upper end of thestack 16 and adapted to be swung thereby through an arc of approximately90 in the horizontal plane between a switch closed position wherein theblade is engaged in the contact 14 (as illustrated in tension electriclines. As is conventional in the art, the

insulators l2 and 16 may be several feet tall and the blade 18 may beseveral feet long to insure an adequate air gap between the conductiveelements in switch open position to prevent striking of an arctherebetween at the potential of the electrical system. Consequently,the rotary stack 16 is journaled in a very heavy bearing secured to thebase 10, and even so the stack and blade impose substantial thrust loadon the bearmg.

The switch shown is of course only illustrative of the switches to whichthis invention is applicable, other examples being shown in US. Pat.Nos. 3,240,887, 3,488,752 and 3,566,055.

According to the present invention, the stack 16 is rotated by means ofa double acting hydraulic cylinder 20 including a reciprocable pistonrod 22 which is secured to and adapted to reciprocate a rack 24 havinggear teeth thereon. The rack 24 meshes with a pinion 26 havingcomplementary gear teeth thereon, the length of the rack in relation tothe size, number and spacing of the gear teeth being such as to rotatethe pinion in the order of about upon each stroke of movement of therack.

Extending between the rotary insulator l6 and the pinion 26 (or theshaft on which the pinion is mounted) is what is herein termed a threebar toggle linkage comprising a crank arm or bar 30 rigidly connectedwith the pinion, a crank arm or bar 32 rigidly connected with the rotaryinsulator adjacent its base, and an intervening bar or link 34 pivotallyconnected at its opposite ends to the two crank arms. Preferably, thelink 34 is comprised of end castings 36 pivotally connected to therespective cranks and each including a pipe clamp 38, and an interveningpiece of pipe 40 secured to the castings by the clamps. By virtue ofthis structure, the spacing between the pinion and the rotary insulatorneed not be precisely measured or precisely maintained when the switchis being installed, since a piece of pipe of whatever length isnecessary can be clamped to the castings 36 and then cut to properlength, which is accomplished very easily in the field at great economy.

As shown in FIG. 2, the crank arm 32 extends at an angle of about 45 tothe vertical plane of the axis of the switch blade. In the switch closedposition, as shown in solid lines in FIG. 2, the crank arm 30 extendssubstantially parallel to said plane, but is pointed slightly towardsaid plane so that the pivot axes of the link 34 and the axis of thecrank 30 are not in a straight line. Any attempt at this time to movethe rotary stack 16 and crank arm 32 in switch opening direction, i.e.,clockwise, would result in turning the crank 30 counterclockwise, whichis not its direction of opening movement. Thus, the linkage is overcenter or over toggle and the blade is locked in closed position byvirtue of its engagement in the contact 14, which preventscounterclockwise movement of the blade, and engagement of the crank 30with a fixed stop 42, which prevents further counterclockwise movementof the crank 30 and thus clockwise movement of the crank 32 and theblade 18. Consequently, the blade is fixedly locked in closed positionagainst both physical and electrical stresses that might be imposedthereon.

When the crank arm 30 is rotated in the clockwise direction by thepinion 26 however, the crank arm 30 moves back on and then out of togglewhereupon the crank 30 andthe link 34 pull the crank 32 clockwise toswing the switch blade to open position. As the blade approaches fullopen position, the crank 30 again moves onto and then over togglerelative to the link 34 and thereafter abuts against a stop 44. Now, anyattempt to move the blade 18 and crank 32 toward closed position, i.e.,counterclockwise, would result in an effort to pull the crank 30 furtherclockwise, which is prevented by the stop 44-, whereby the blade 18 islocked in full open position and cannot be swung toward the closedposition, except upon actuation of the cylinder and rotation of thepinion 26.

Thus, the three bar linkage 30, 32, 34, while providing a very compactand economical structure facilitating field erection of the switch,additionally provides the safety features of having the switch bladefully locked in both its switch open and its switch closed positions.

Turning now to H6. 3, the preferred embodiment of the hydraulic cylinder20 and its operating mechanism are shown compactly mounted in anenclosure or housing 50. The mechanism preferably comprises an electricmotor 52 driving a hydraulic pump 54 for supplying hydraulic fluid underpressure selectively to the opposite ends of the cylinder 20. Areservoir 56 for hydraulic fluid is provided, and a manually operatedpump 58 is also interconnected with the pump 54 to accommodate manualoperation of the mechanism in the event of an electric power failure.

Pressure fluid from the pump, either the motor operated pump 54 or thehand operated pump 58 is supplied to a selected end of the cylinder 20under the control of a four-way valve 60 which operates to vent one endof the cylinder 20 to the pump inlet while connecting the other end ofthe cylinder 20 to the pump outlet. The valve 60 is under the selectivecontrol of a pair of solenoids 62 for automatic operation, or in theevent of a power failure, under the selective manual control provided bya pair of push buttons 64. Preferably, the pumps are capable ofsupplying hydraulic fluid to the cylinder at pressures up to 2,500 psi.,although the normal operating range may be about 200 to 500 psi.,depending upon the existing resistance to movement of the blade 18, forexample the comparative resistance factors of clear summer weather andsever winter conditions wherein several inches of ice may build up onthe blade 18 and its contact 14. Preferably, the motor 52, pumps 54 and58, reservoir 56 and valve 60 are secured to a common mounting plate 66for assembly as a unit into the housing 50.

The cylinder 20 is preferably pivotally mounted on a wishbone extension68 of a bearing assembly 70 so as to accommodate minor degrees ofcomponent misalignment, the assembly 70 being fixedly secured to thehousing 50. The rack 24 is secured to the outer end of the piston rod 22and is preferably guided for reciprocal movement in slide bearingsurfaces 72 formed in or on the assembly 70. For example, the slidebearings may comprise a grooved raceway for the rack, or may consist ofa rotatable bearing mounted on a vertical axis parallel to and behindthe axis of rotation of the pinion 26 for holding the rack in mesh withthe pinion.

The assembly '70 further provides a pair of vertically spaced annularbearings 74 to opposite sides of the rack 24 for reception therein of arotatable shaft 76 to which the pinion 26 is secured in the spacebetween the bearings 74. The assembly thus serves to mount and guideboth the pinion 26 and the rack 24 whereby the same are mounted andretained in meshed engagement with one another. The shaft 76 extendsupwardly through a sealed opening in the housing 50 and carries at itsupper end the pinion crank 30 for effecting the switch actuatingmovements previously described.

The housing 50 thus serves as a sealed enclosure for all mechanismcomponents bearing reference numerals 52 and higher, whereby thesecomponents are completly shielded and protected from the adverse weatherconditions to which the switch per se is exposed.

Adjacent the lower end thereof, the shaft 76 carries a pair of actuatingarms 78 for engagement respectively with a pair of adjustably mountedlimit switches 80 or the like which serve to discontinue operation ofthe motor 52 when the shaft 76 and crank 30 reach the respective ends oftheir arcuate path of movement, i.e., with the crank 30 abuttingrespectively against the stops 42 and 44.

For the sake of convenience, the stops 42 and 44 have been illustratedand described herein as being associated with the crank 30, whereby toclarify their cooperative relationship and functions. However, in acommercial embodiment of the switch mechanism, it would be preferablenot to have the stops exposed to the weather, but rather to mount thesame within the housing 50; for example, to cooperate with an additionalcrank arm on the shaft 76, or in the alternative to build the stopsdirectly on the rack 24.

At its lower end, the shaft 76 may carry a further crank arm or cam 82for performing additional control functions as may be desired, such forexample as closing the circuits of remote indicator lights or the like.

In a preferred embodiment of the above-described apparatus, the pumps 54and 58 produce a normal operating pressure of 200 to 500 psi., have anormal full load pressure of 1,500 psi., and are preferably capable ofproducing up to 2,500 psi. fluid pressure. The cylinder 20 may forexample have a 2 /2 inch bore and a piston stroke of 8 inches. With thepower amplifying charac'teristics of the rack and pinion, thisarrangement results in a power output at the shaft 76 of 15,000 inchlbs. at 1,500 psi. fluid pressure. The three bar linkage 30, 32, 34 thenfurther amplifies the power output to provide in the 1,500 psi. exampleapproximately 40,000 lbs. of force at the blade end as it enters orleaves the contact 14. Thus, extremely great force is provided forforcing the blade into and out of the stationary contact. Experimentaltests have been conducted with this apparatus under laboratoryconditions of extreme icing, and the switch has never failed to open orto reach fully closed position in normal operation of the mechanism ofthis invention.

Because of the force produced, the switch blade 18 may be swung directlyinto extremely high pressure limited area contact with the contactstructure 14 without necessity for rotating the blade about its own axisas has been necessary in switches such as those illustrated anddescribed in Pat. 3,240,887 and 3,488,752. By virtue of this capability,a side break switch such as shown herein, or a circuit breaker such asshown in US. Pat. No. 3,566,055, can now be closed against very heavyforces, both physical and electrical, and specifically can be used toclose even a high current faulted circuit since the direct contactprovided by elements M and 18 mitigates the arcing that inherently wouldoccur under these conditions with the switches of U.S. Pat. Nos.3,240,887 and 3,488,752.

The three bar linkage 30, 32, 34 provides the particular advantage ofimparting a cyclic movement to the rotary stack 16 and the blade 18wherein the blade upon each movement thereof, either opening or closing,is first moved slowly to provide relatively gentle blade accelerationunder conditions of ahigh force to movement ratio, is then swung rapidlythrough the major part of its arc of movement, and finally is gentlydeccelerated to a smooth shockless stop, again with a high force tomovement ratio. This is accomplished by virtue of the relativedispositions of the cranks 30 and 32 and the fact that the crank 30,adjacent the opposite ends of its 180 or more path of movement, ismoving substantially perpendicular to the direction of movement of thecrank 32 whereby very little movement is imparted to the crank 32 foreach degree of movement of the crank 30. On the other hand, in that partof the movement of crank 30 which generally parallels the path ofmovement of the crank 32, there is essentially a one-to-onerelationship, whereby the crank 32 is moved essentially at the same rateas the crank 30, and thus much faster than at the ends of the path ofmovement of the crank 30. Manifestly, due to the fact that the crank 30is moving arcuately, there is a smooth transition between the twoextreme conditions above defined. Thus, the blade i8 is in sequencegently accelerated, swung rapidly and then gently deccelerated, which isof very substantial advantage in switch operation especially inoperation of switches such as disclosed in U.S. Pat. No. 3,566,055.

Also, as earlier described, the three bar linkage provides a positiveblade lock in both of its end positions.

A particular feature of the hydraulic mechanism of the invention is thatthe opposite ends of the cylinder 20 are directly connected to the inletand the outlet of the pumps 54 and 58 (through the four-way valve 60)and are never dumped to the reservoir 56. The reservoir 545 is simply ina stand-by condition to accommodate replenishment of lost fluid andexpansion space should there be a surge of fluid. Basically, there is aclosed hydraulic circuit between the pump and the cylinder, whereby thephysical link provided by the hydraulic fluid is a solid link, not aresilient link. Thus, piston operation is always positive and always thesame, even at widely disparate temperature ranges.

Also, because there is a solid hydraulic link, hydraulic stops may beprovided at one or both ends of mechanism operation (for example wherethe hydraulic system is used independently of the three bar linkage, orthe latter is not made to over-toggle at one end of blade movement, oras a further safety factor) by the provision of poppet valves in thehydraulic lines to the cylinder, whereby to lock the fluid in thecylinder thereby to prevent movement of the rack and pinion.

The presence of the manually operated pump 58 in parallel with the pump54, affords the particular advantage that full force for either openingor closing the switch can be provided even, and perhaps mostimportantly, in the event of a power failure. Mechanical switchoperating mechanisms cannot provide this advantage, since they areinherently limited to the amount of force personnel can apply to themechanism. Here, the same operating force can be applied, at the samespeed and with the same characteristics of switch movement, even in theevent of power failure.

Thus, the objects and advantages of this invention have been shown to beattained in a convenient, economical and practical manner.

While l have shown and described what I regard to be the preferredembodiment of our invention, it is to be appreciated that variouschanges, rearrangements and modifications may be made therein withoutdeparting from the scope of the invention as defined by the appendedclaims.

What is claimed is:

1. Operating mechanism for a high tension electric switch having arotatable input shaft, comprising hydraulic pump means, a double-actinghydraulic cylinder having a piston and a piston rod reciprocatedthereby, valve means for supplying fluid under pressure from said pumpmeans selectively to the opposite ends of said cylinder for venting theend of the cylinder opposite the end to which fluid under pressure issupplied, a rack connected to said piston rod for reciprocation thereby,a pinion meshed with said rack for rotation in opposite directions uponreciprocation of said rack, a bearing assembly for said rack and andpinion comprising slide bearing means for guiding the reciprocalmovements of said rack, a pair of annular bearings to opposite sides ofsaid slide bearing means, a shaft journalled in said annular bearings,said pinion being secured to said shaft in meshed engagement with saidrack, and means for connecting said pinion to the switch input shaft,said cylinder and said rack and pinion multiplying the fluid poweroutput of said pump and providing high operating forces for opening andclosing the switch.

2. Operating mechanism for a high tension electric switch having arotatable input shaft, comprising a power drive shaft rotatable inopposite directions, a first crank connected with said drive shaft foroscillation thereby, a second crank connected with the switch inputshaft, a link extending between and pivotally connected at its ends tosaid cranks, said link comprising a pair of end members pivotallyconnected respectively to said cranks, a a clamp on each of said endmembers, and a straight link piece extending between said members andsecured thereto by said clamps, said first crank being oscillated bysaid drive shaft through an arc of movement slightly greater thanwherein the arcuate movement is principally to one side of its axis ofrotation between first and second end positions in both of which thepivotal connection between first crank and said link is beyond said oneside of a line drawn between said axis and the pivotal connection ofsaid link and said second crank, and stop means to the side of saidfirst crank opposite said one side engageable by said first crank in itssaid end positions, whereby the linkage comprised of said cranks andsaid link is over toggle and abutted against a stop means in each of itsend positions to prohibit reversal of movement of said second crankexcept by operation of said first crank.

3. Operating mechanism for a high tension electric switch having arotatable input shaft, comprising a rack, power means for reciprocatingsaid rack, a pinion meshed with said rack for rotation in oppositedirections upon reciprocation of said rack, a first crank secured tosaid pinion for oscillation thereby, a second crank secured to saidinput shaft, a link extending between and pivotally connected at itsends to said cranks, said first crank being movable through an arc inexcess of 180 between first and second end positions and having anovertoggle relationship with said link in both of said end positions,and stop means engaged by said first crank means in both said first andsecond overtoggle end positions, whereby movement of said second crankmeans in either direction is prevented without actuation of said powermeans.

4. The operating mechanism of claim 3 wherein the path of movement ofsaid first crank adjacent said first and second end positions issubstantially perpendicular to the direction of movement of said secondcrank, whereby upon each rotation of said first crank said second crankis slowly accelerated with a high force to movement ratio, moved rapidlyand then slowly decelerated with a high force to movement ratio.

5. Operating mechanism for a high tension electric switch having arotatable input shaft, comprising a drive shaft mounted in spacedparallel relation to said input shaft, a first crank secured to saiddrive shaft, a second crank secured to said input shaft, a linkextending between and pivotally connected at its ends to said cranks,means for oscillating said drive shaft and said first crank through anarc of movement slightly greater than between first and second endpositions, said first crank in each of its said end positions extendinggenerally in the direction of movement of said second crank so that saidfirst crank when in the vicinity of its end positions moves generallyperpendicular to the direction of movement of said second crank, thepivotal connection between said first crank and said link in each ofsaid end positions being located beyond a line drawn between the axis ofrotation of said first crank and the pivotal connection of said link andsaid second crank so that the linkage comprised of the two cranks andsaid link is overtoggle in each end position, and stop means engaged bysaid first crank in each of its said end positions for retaining thesame against further overtoggle movement and thereby locking the linkagein both end positions.

1. Operating mechanism for a high tension electric switch having arotatable input shaft, comprising hydraulic pump means, a double-actinghydraulic cylinder having a piston and a piston rod reciprocatedthereby, valve means for supplying fluid under pressure from said pumpmeans selectively to the opposite ends of said cylinder for venting theend of the cylinder opposite the end to which fluid under pressure issupplied, a rack connected to said piston rod for reciprocation thereby,a pinion meshed with said rack for rotation in opposite directions uponreciprocation of said rack, a bearing assembly for said rack and andpinion comprising slide bearing means for guiding the reciprocalmovements of said rack, a pair of annular bearings to opposite sides ofsaid slide bearing means, a shaft journalled in said annular bearings,said pinion being secured to said shaft in meshed engagement with saidrack, and means for connecting said pinion to the switch input shaft,Said cylinder and said rack and pinion multiplying the fluid poweroutput of said pump and providing high operating forces for opening andclosing the switch.
 2. Operating mechanism for a high tension electricswitch having a rotatable input shaft, comprising a power drive shaftrotatable in opposite directions, a first crank connected with saiddrive shaft for oscillation thereby, a second crank connected with theswitch input shaft, a link extending between and pivotally connected atits ends to said cranks, said link comprising a pair of end memberspivotally connected respectively to said cranks, a a clamp on each ofsaid end members, and a straight link piece extending between saidmembers and secured thereto by said clamps, said first crank beingoscillated by said drive shaft through an arc of movement slightlygreater than 180* wherein the arcuate movement is principally to oneside of its axis of rotation between first and second end positions inboth of which the pivotal connection between first crank and said linkis beyond said one side of a line drawn between said axis and thepivotal connection of said link and said second crank, and stop means tothe side of said first crank opposite said one side engageable by saidfirst crank in its said end positions, whereby the linkage comprised ofsaid cranks and said link is over toggle and abutted against a stopmeans in each of its end positions to prohibit reversal of movement ofsaid second crank except by operation of said first crank.
 3. Operatingmechanism for a high tension electric switch having a rotatable inputshaft, comprising a rack, power means for reciprocating said rack, apinion meshed with said rack for rotation in opposite directions uponreciprocation of said rack, a first crank secured to said pinion foroscillation thereby, a second crank secured to said input shaft, a linkextending between and pivotally connected at its ends to said cranks,said first crank being movable through an arc in excess of 180* betweenfirst and second end positions and having an overtoggle relationshipwith said link in both of said end positions, and stop means engaged bysaid first crank means in both said first and second overtoggle endpositions, whereby movement of said second crank means in eitherdirection is prevented without actuation of said power means.
 4. Theoperating mechanism of claim 3 wherein the path of movement of saidfirst crank adjacent said first and second end positions issubstantially perpendicular to the direction of movement of said secondcrank, whereby upon each rotation of said first crank said second crankis slowly accelerated with a high force to movement ratio, moved rapidlyand then slowly decelerated with a high force to movement ratio. 5.Operating mechanism for a high tension electric switch having arotatable input shaft, comprising a drive shaft mounted in spacedparallel relation to said input shaft, a first crank secured to saiddrive shaft, a second crank secured to said input shaft, a linkextending between and pivotally connected at its ends to said cranks,means for oscillating said drive shaft and said first crank through anarc of movement slightly greater than 180* between first and second endpositions, said first crank in each of its said end positions extendinggenerally in the direction of movement of said second crank so that saidfirst crank when in the vicinity of its end positions moves generallyperpendicular to the direction of movement of said second crank, thepivotal connection between said first crank and said link in each ofsaid end positions being located beyond a line drawn between the axis ofrotation of said first crank and the pivotal connection of said link andsaid second crank so that the linkage comprised of the two cranks andsaid link is overtoggle in each end position, and stop means engaged bysaid first crank in each of its said end positions for retaining thesame against further overtoggle moveMent and thereby locking the linkagein both end positions.